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Marine Boiler Shop.                         319

required is very apparent, the importance of ample provision for
lifting being a point upon which Mr. Tweddell always insisted.

Plate XVI. represents the interior of a Marine Boiler Shop.
B is a Stationary Riveter, exactly as in Fig. 298, and a circular
pit c admits a large marine boiler when riveting. As it is difficult
to obtain nicety of vertical movement in the travelling crane D,
an intermediate cylinder or Hydraulic Adjuster, E, forms a very
useful adjunct. The Progressive Flanging Machine F was shewn
at Fig. 290, and the crane A lifts the plate to or from the fire. A
plan view of the latter is given at G, where the dotted lines shew
the plate being heated. H is the Locomotive type of Marine
Boiler, much used for the smaller boats, the riveting of which is
performed as in Plate XV. A Marine Boiler is given at j, having
the furnace mouth riveted round with a small bear K, which also
joins the ' Adamson' flues at L. At M the boiler is being closed
by a powerful bear-type machine, having plate-gripping tool, and
hung from the travelling crane through the medium of1 the
adjuster N. The last-finished flange is here turned outward, as
^advocated by Mr. Tweddell, to secure good machine riveting
throughout; but as many makers prefer an internal flange, to
save cargo space or reduce weight, the riveter at p has been
recently devised. Jt is slung from its centre of gravity, and the
free arm lowered into the boiler, as shewn dotted. When raised,
the latter serves as * dolly/ and can be adjusted in length to suit
various diameters of boilers. A hole must be left at Q, to be
covered afterwards by the plate carrying the central nest of tubes,
the final riveting of which is performed by hand.

The diagram in Fig. 301 shews the arrangement of hydraulic
tools on TweddelFs system applied to Shipbuilding. A is a keel
riveter, supported by parallel motion and balance weight, so that
it may be raised or lowered to reach the keel in any position, yet
remain with jaws vertical The gunwale riveter at E is similar in con-
struction, H shews a small travelling jib crane, carrying a direct-
acting machine for riveting the combings of hatchways, j and K
are Hydraulic winches, and G a punching or shearing machine. B *
is another jib traveller carrying the Large lever riveter c for finishing
the double bottom, and the machine B, supported by a crane with
two movements, is for riveting the keelson. A special carriage F